1. Technical Field
The invention relates to the field of data communications. More specifically, the present invention relates to a method of controlling data transferred on a segmented phone line local area network (LAN) using a virtual LAN (VLAN) header inserted into a frame header to identify which virtual subnet (VLAN) of the segmented phone line LAN the data may be transferred to.
2. Description of the Related Art
It is well known in the art that the Home Phone Networking Alliance (HPNA) has created standardized protocols for establishing phone line LANs for use in a small office/home office (SOHO) environment. Several vendors have developed phone line LANs based on these protocols which allow users to merely plug their computers or peripheral devices (nodes) into the nearest phone jack without disrupting normal phone service.
An example of a prior art phone line LAN topology is a topology that includes a number of end-systems (nodes), such as personal computers, mobile computers, printers, parallel ports, network cameras, traditional phones, web phones, TV set-top-boxes, cameras, scanners, a residential gateway or any other appliance having a network interface device capable of connecting via a phone line. The end-systems are connected via phone lines to phone jacks which in turn are connected via phone lines. The phone line LAN can be connected to a global computer network via the residential gateway or through a dial up connection or the like.
Network interface devices which are capable of communicating data over a phone line LAN are available. Such devices are used to connect the nodes to the network. However, phone line LANs using the standard HPNA protocols do not provide a means for segmenting the phone line LAN into virtual subnets (VLANs).
Traditional LANs which allow segmentation into VLANs are costly or unsightly as they require either professional network cable installation or the tracking of large quantities of network cable throughout the SOHO. Additionally, these LANs require hubs, switches or routers to segment the network into VLANs.
Therefore, there is a strong need in the art for a method which would allow VLAN segmentation of the phone line LAN without the use of hubs, switches or routers.
The present invention is a method of segmenting a physical phone line LAN into virtual subnets called VLANs. VLANs can be seen as analogous to a group of nodes perhaps on multiple physical LAN segments, that are not constrained by their physical location and can communicate as if they were on a common LAN. In order to segment the LAN into VLANs, each node of the LAN must be assigned a VLAN identifier (VLAN ID). Next, each node must be assigned to at least one VLAN. After assigning each node to a particular VLAN, the assignment information is used by the network interface device to generate a VLAN header, including a VLAN tag and the VLAN ID. The VLAN header is inserted into a frame header of the data to be transmitted. The data is transmitted over the LAN to a destination node. A network interface device at the destination node strips the VLAN header and passes a remaining part of the frame to a software driver.
A VLAN header is a unique frame identifier which is added at a source node within each frame header to be transmitted on the phone line LAN. This header information designates the VLAN membership of each frame. The frame is received by the appropriate destination node based on the VLAN header and MAC address. Upon reaching the destination node location, the VLAN header is removed (stripped) from the frame by the device driver and a remaining part of the frame is forwarded to a software driver. The use of a VLAN header to virtually segment a phone line network LAN provides a powerful mechanism for controlling the flow of data and access to applications while remaining non-intrusive to the network and applications.
According to one aspect of the present invention, a method of communicating within a phone line LAN includes the assignment of a unique VLAN ID to each node of a VLAN. A VLAN header is attached at a source node of the frame to each frame to be communicated within the VLAN. The VLAN header contains identification information associated with the VLAN. The VLAN header is inserted by a network interface device driver into a frame header. Data communication within the VLAN is controlled at the nodes of the VLAN by examining incoming frames for the presence or absence of the VLAN header. The VLAN header is stripped at the destination nodes of the VLAN from the frame header and a remaining part of the frame is passed to a software driver.
According to another aspect of the invention, a method of communicating within a plurality of VLANs, which include parts of a phone line LAN, includes registering each node of the LAN to at least one VLAN by assigning a unique VLAN ID to each node. A VLAN header is attached at a source node of the frame to each frame to be communicated within a VLAN. The VLAN header contains identification information associated with the VLAN. The VLAN header is inserted by a network interface device driver into a frame header. Data communication within the VLAN is controlled at the nodes of the specific VLAN by examining incoming frames for the presence or absence of the VLAN header associated with the specific VLAN. At destination nodes of the specific VLAN, the VLAN header is stripped from the frame header and a remaining part of the frame is passed to a software driver. Thus, the VLAN headers ensure that the frame to be communicated within the specific VLAN remains within the nodes of the specific VLAN, exclusively.
According to yet another aspect of the present invention, a method of communicating within a VLAN, which includes a phone line LAN having nodes of a mixed network, includes the assignment of a unique VLAN ID to each node of the VLAN. A VLAN header is attached to each frame to be communicated within the VLAN at a source node of the frame. The VLAN header contains identification information associated with the VLAN. The VLAN header is inserted by a network interface device into a frame header. Data communication within the VLAN is controlled at the nodes of the VLAN by examining incoming frames for the presence or absence of the VLAN header. At destination nodes of the frame, the VLAN header is stripped from the frame header and the remaining part of the frame is passed to a software driver.
According to yet another aspect of the present invention, a VLAN may be further defined at the network layer with segmentation commonly based on protocol type and network address. This type of VLAN segmentation requires subnet address mapping to VLAN groups. The transmitting device associates the (source) node MAC address to a VLAN based on the subnet address. Additionally, the transmitting device determines the other network nodes that belong to the same VLAN.
In another embodiment, a 32-bit (4 byte) VLAN ID field is applied to every frame as it is forwarded across links; each frame carries a unique identification and is forwarded to the device that has been configured with the same VLAN identification. Only frames that are destined for addresses outside the VLAN need to proceed to a hub, switch, router, bridging server or the like for forwarding. At the destination device the 32-bit address is removed. VLANs are carried transparently across these networks, and require no configuration or intervention by network managers.
The present invention has the ability to concurrently handle layer 2 and layer 3 VLANs, as well as the ability to interconnect VLANs both within the LAN and across LANs. Layer 2 is at the data link level and is defined by port or MAC address. Layer 3 is at the network level and is defined by an Internet Protocol (IP) address or the like.
The network interface device driver has a way of understanding VLAN membership (that is, which nodes belong to which VLAN) when network traffic arrives from other nodes. In general, layer 2 based VLANs (defined by port or MAC address) must communicate VLAN membership explicitly, while VLAN membership in Internet Protocol (IP) based VLANs is implicitly communicated by the IP address.
To the accomplishment to the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent in the following detailed description of the invention when considered in conjunction with the drawings.